I have 3 hens who are about 8 months old and they have never laid an egg. I also have a 8 month old hen that started laying eggs very regularly a couple months ago. But I had to put them all on antibiotics and ever since then she has only laid 2 eggs in three months. I have 2 10 month old hen's who have been laying regularly except for here lately since one is molting. I have no idea what is wrong with my other hens. Was the antiobiotic I had them on caused some reproduction problems or what else could be wrong with my girls.